For example, in a conventional apparatus as disclosed in Patent Literature 1, a plurality of cylindrical winding layers are overlaid to form a multilayer cylindrical winding. Between adjacent cylindrical winding layers, there is provided an interlayer insulator for insulating the cylindrical winding layers. In addition, each cylindrical winding layer of the multilayer cylindrical winding (partial coil assembly) is constituted of a plurality of part windings (partial coils). The plurality of part windings are connected in parallel. Further, between adjacent part windings, there is formed a refrigerant flow path for cooling oil (refrigerant) to flow.
Further, for example, in a conventional apparatus disclosed in Patent Literature 2, a plurality of spacing pieces are disposed with spaces between adjacent metal sheets. By the plurality of spacing pieces, the refrigerant flow path is formed between the adjacent metal sheets.